The invention relates to a hub attachment assembly. The assembly includes a driveshaft with external splines at its shaft end, a slide-on hub with a shaft bore having corresponding internal splines, and an axial securing mechanism. The axial securing mechanism includes a resilient snap ring which engages opposed recesses in the two sets of splines.
There exist several prior art designs of such assemblies, some of which will be described below by way of example. However, the art has specific disadvantages.
According to a first prior art design, a fixed radial stop shoulder is provided on the hub at the driveshaft towards the shaft shank. The hub, via an end face, is in contact with the stop shoulder. Axial fixing or attaching at the shaft end is effected by a securing element which engages an annular groove.
A problem with this design is the axial distance between the stop shoulder and recess has to be dimensioned very accurately. Thus, the tolerances of the axial length of the hub and of the thickness of the snap ring are taken into account. Furthermore, in the course of production, the axial length of the external splines at the driveshaft relative to the position of the stop shoulder is very accurately observed to ensure that the stop shoulder is not damaged. The internal splines in the hub, relative to the profile run-out at the driveshaft, must not extend over the entire length of its shaft bore.
According to a second prior art design with basically identical first and second stop means, it is proposed, as above, to insert an intermediate ring between the stop shoulder on the shaft and the hub. In this case, it is possible to reduce the problem of accurately dimensioning the profile run-out, which may axially extend beyond the length of the hub towards the shaft shank. A disadvantage is that it is necessary to provide an additional annular part. Thus, with respect to the axial distance between the annular shoulder and recess, further tolerances are taken into account.
Especially with cold-formed monoblock tubular shafts, the required stop shoulder is difficult to produce for the two above-mentioned designs. In the case of monoblock tubular shafts, it is necessary, for compensation purposes, to provide a material accumulation underneath the splines. The blank required for this purpose, with a variable wall thickness, is expensive to produce.
In the case of solid shafts, the height of the stop shoulder determines the diameter of the starting material. Thus, the shoulder defines the disadvantageous machining volume. Such recessed stop shoulders weaken the torque-loaded cross-section and, in addition, lead to an excessive stress level.
According to a third prior art design, a snap ring is provided which simultaneously engages corresponding annular grooves cut into the respective splines of the driveshaft and of the shaft bore of the hub. The disadvantage in this case refers to the notch effect relative to the driveshaft and hub, especially if, with reference to the axial length of the hub, the annular grooves are orientated towards the adjoining shaft shank and are thus, relative to the driveshaft, positioned in the region of torque flow. Furthermore, the assembling and dismantling operations are very complicated with these designs.